Discharge lamp, cutout device, and method of manufacture



Jan. 22, 1946. A; H. LAIDIG 2,393,253

I DISCHARGE LAMP, CUT-OUT DEVICE, AND METHOD OF MANUFACTURE Filed June 26, 1942 ATTORNEY Patented Jan. 22, 1946 DISCHARGE LAMP, CUTOUT DEVICE, AND METHOD OF MANUFACTURE Alfred H. Laidig, Bloomfield, N. J., asslgnor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 26, 1942, Serial No. 448,556

3 Claims.

This invention relates to gaseous discharge lamps and, more particularly, to fluorescent lamps and the like operable from the usual sources of domestic electrical energy.

The principal object of my invention, generally considered, is to provide a discharge lamp with simple starting means, while at the same time avoiding loss of power in case said lamp fails to operate within a reasonable length of time.

Another object of my invention is the provision of an electric discharge lamp enclosing a pair of electron-emissive filamentary electrodes, and means associated with one of said electrodes for opening the circuit therethrough after a reasonable number of unsuccessful attempts to start.

A further object of my invention is the provision of a low temperature fuse disposed close to one of the filamentary electrodes of a discharge lamp for opening the starting circuit in case starting has been unsuccessful after a reasonable number of attempts.

A still further object of my invention is the insertion of a fuse in a device, such as a discharge lamp, for opening the starting circuit to said lamp in case the latter is defective, as determined by failure to start within a reasonable length of time.

An additional object of my invention is the method of manufacturing a discharge lamp having a fuse incorporated therewith, whereby said lamp may be baked at a temperature high enough to melt the fuse without destroying its effectiveness for subsequent use.

Other objects and advantages of the invention,

relating to the particular arrangement and construction of various parts, will become apparent as the description proceeds.

Referring to the drawings:

Fig. 1 is a fragmentary elevational view, with parts broken away and a starting circuit shown diagrammatically, illustrating a lamp embodying my invention.

Fig. 2 is a fragmentary elevational view, with parts in section, of the electrode shown in the left hand end of the lamp of Fig. 1, on a larger scale.

Fig. 3 is a transverse sectional view on the line III-III of Fig. 2, in the direction of the arrows.

Fig. 4 is a transverse sectional view, corresponding with Fig. 3, but showing a modification.

Fig. 5 is a fragmentary sectional view on the line V-V of Fig. 2, in the direction of the arrows.

Fig. 6 is a fragmentary sectional view, corresponding with a portion of the device shown in Fig. 2, but before melting the readily fusible metal and assembly of the second lead section therewith. v

Fig. 7 is a plan of the parts shown in Fig. 6. Fig. 8 is a fragmentary elevational view of the .left hand or fused end portion of the lamp shown in Fig. 1, with its axis vertical and connected for being exhausted.

Fig. 9 is a sectional view of a fuse or cut-out member construction, generally as shown in Fig. 2 but modified.

Fig. 10 is a transverse sectional view on the line X--X of Fig. 9, in the direction of the arrows.

Fig. 11 is a transverse sectional view on the line XI-XI of Fig. 9, in the direction of the arrows.

Fig. 12 is a fragmentary view corresponding generally with Fig. 2 but showing a modification.

Fig. 13 is a transverse sectional view corresponding to Fig. 4, but showing another modification.

The Dench patent, No. 2,200,443, discloses a discharge lamp of a type contemplated by the present application and a circuit for initiatin operation thereof, In accordance with said patent the filamentary electrodes 8 and 1 are first operated in series through an inductor device, such as a choke coil 9, and an automatically responsive cut-out device l3, whereby said filamentary electrodes 6 and I are first heated to incandescence, whereupon the circuit therethrough is broken and the lamp is supposed to be started by a voltage surge caused by breaking the circuit through the inductor device 9. However, sometimes discharge lamps fail to operate under such conditions, as because they are defective in lacking sufficient electron emission material or for some other reason, whereupon the starting circuit therethrough will be repeated as long as the starting device is in operable condition and the circuit thereto is not broken. It is one of the purposes of my invention to produce a lamp which automatically discontinues operation of such a starting device when the discharge lamp is shown to be inoperable or defective, by failure to start after a reasonable number of attempts.

Referring to the drawing in detail, and first considering the embodiment of my invention illustrated in Figs. 1 to '7, inclusive, a gaseous electric discharge device 21 is shown comprising an enclosing envelope 22 and filamentar electrodes 23 and 24, respectively supported on flares 25 and 26 forming mounts connected to the opposite ends of said envelope and surrounded by a gaseous filling preferably admixed with a small proportion of mercury vapor. The lamp is shown based at 2'! and 28, the latter of said bases being marked top in order to indicate the position of oper-- ation in case the lamp is used other than horizohtally. The bases are respectivel provided with contact posts 29, Si, 32 and 33 in order to provide for heating the filamentary electrodes as well as sup-plying the discharge current to the lamp.

I will now describe a preferred embodiment of my invention with a conventional starting circuit, but I do not wish to be limited to the exact details. As in the Bench patent, previously identified, one terminal or contact post 29 of the electrode 23 is connected through an inductance element or choke coil 34 to one side of a source of electrical supply, such as the customary household power line of 115 or 230 volts. Likewise one terminal 32 of the electrode 24 is connected through switch 35 to the opposite side of said source of power.

The remaining terminals of the electrodes, as through contact posts 3| and 33, are connected through an automatic cut-out device 35, with a condenser 31 preferably in parallel therewith to minimize sparking. This device in the present embodiment takes the form of an auxiliary discharge or glow tube comprising gas-filled envelope 49 containing a bi-metallic strip 38, the free end portion of which functions as a contact 38 for engaging a cooperating contact member 4 i The device 36 functions as a glow tube for'the passage of electric current upon the application of 21 voltage of from about 90 to 100.

By virtue of the circuit described, when the switch 35 is first closed, current will flow from the source of supply through the inductance element 34, the electrode 23,'automatic device 36 and electrode 24 back to the source of supply. If the lamp filaments are intact and the device 36 is working properly, a glow discharge will occur between the members 38 and 4|, heating the bi-metallic strip 38 and causin the same to flex and its end portion 39 contact with member 4|, thereby extinguishing the discharge. This short-circuits the electrode 23 and '24 across the source of supply, heating. them to electron-emitting temperatures. However, after the lapse of a short length of time the 'bi-metallic'element 38 cools, causing it to flex back to its original position, as shown in Fig. 1, and breaking the connection between the contacts 39 and 41, interrupting the heating circuit and the choke coil 34 causing an inductive voltage surge to start a discharge between the electrodes 23 and 24. If, however, for some reason such as a defec tive or worn out condition, for example, the lamp 2! fails to start after a reasonable number of attempts, the series circuit through the electrodes 23 and 24 will be opened by a cut-out device 42 disposed adjacent one or both ends thereof, which will now be described in detail.

Referring specifically to Figs. 2, 3, 5, 6 and '7, it will be seen that the electrode 23, which is desirably a tungsten filament of the coiled-coil type coated with electron-emission material, such as alkaline earth oxide or oxides, receive current through lead-in conductors 43 and 44 to which are attached arcing prongs45 and '46 functioning as operating anodes to protect the electron emission material on the filament 23. The lead-in conductor 44 passes through the press 41, which is that having the exhaust tube 56, and another conductor, designated b the reference character 48, is offset therefrom. The adjacent end portions of said conductors are received in corresponding apertures in an insulating boat or receptacle 49,

forming the housing of the circuit-breaking or cut-out device 42, desirably passing through the base 5| of said boat from opposite sides and connected to said boat by having the ends in gripping relationship therewith as indicated at 52 and 53.

Th boat 5| may be of any heat resisting insulating material such as porcelain or other ceramic, glass, or the like, and the open side thereof desirably abuts the free or inner portion of the press 41, as shown most clearly in Fig. 2. In order to connect the conductors 44 and 48 to provide for an operative circuit, the boat is partially filled with the metallic material 54, preferably solid at room temperatures, but fusible at relatively low tem peratures, such for example as those above about 200 C.

Such a material may consist of an alloy of lead, tin and bismuth, in the proportion by weight of approximately 70.9% lead, 9.1% tin and 20.0% bismuth which melts at about 453.2 F. although it will be understood that some other alloy having suitable fusion characteristics may be employed. Such material maybe applied in the form of a piece of wire or sheet 30 when the boat is disposed with its open end uppermost, as shown in Figs. 6 and '7. These figure show such a sheet 30 of metal bent to approximately U shape and placed so as to line a portion of the interior of the boat 5|. The lead-in conductor section 48 is in position so as to hold an intermediate portion of said sheet against one end of said boat. The other lead-in conductor section 44 may then be applied as shown in Fig. 2.

It is unnecessary to initially fuse said material around the conductorsections '44 and 48, although this may be done if desired, because that will be taken care of during the process of exhaust, illustrated in Fig. 8, where a heat treating operation is shown applied to one end DOrtiOn of the lamp 2| by means of a high frequency coil 55, while an exhaust operation is being performed on the lamp through exhaust tube 58. Th temperature during exhaust is high enough to cause the metal or alloy, 54, as in the form of sheet 30, to melt and form a. good connection between the lead sections 44 and 48, as shown in Figs. 2 and 5, said metal even when fused not running out of the boat 48 as long as the lamp is in the position shown in Fig. 8, which positionis necessarily taken on exhaust because of the location of the exhaust tube 56, and maintained'until the lamp has cooled sufficiently to prevent loss'of the fusible material'54 from the boat 49.

In order to prevent undesired melting of the material 54 during normal operation of the lamp 2!, the portions of the lead sections 44 and 48 disposed toward the electrode 23 are desirably coated with aluminum as shown at 51 and 58, or otherwise shielded. Repeated futile attempts to start the lamp by energizing the filamentary electrodes to incandescence causes a sufficient transfer of heat to the material 54 through the lead section 48 and by radiation so that said material melts and runs out of the boat or away from the lead sections to break the circuit through the electrodes 23 and 24, and thereby terminate the loss of power in attempted starting of the lamp.

In order to effect such a result, the lamp is necessarily operated in such a position that the metal 54, after being melted, will run out of the boat or so that the ci'rcuit :betwen the lead sections 44 and 48 is broken. Thus, the endof the lamp marked "top "should either be above or not 'too much below the elevation of the opposite end, and the boat should be so positioned that its long axis is vertical or other than horizontal. Should the lamp be burnt vertically with the top marked end at its bottom, the operation of the lamp would not be interfered with, except that the cut-out feature would be eliminated and the lamp would when defective always try to start.

In other words, if the metal-containing boat 49 is disposed with its axis perpendicular to the plane of the lead-in conductors, as shown in Fig. 4, rather than in the plane thereof, as shown in Figs. 2 and 3, then the preferable position for operating the lamp, if horizontal, is when rotated from about 45 to 90 about its axis.

In order to prevent positioning the lamp dur ing operation, so as to be ineffective for accomplishing the purpose of my invention, one cutout device 42, as shown in Fig. 3 may be associated with one end of the filamentary electrode at the exhaust-tube end of the lamp 2!, and an other such device 42, as shown in Fig. 4, with the other end of the filamentary electrode, thereby insuring that the circuit will be broken without fail under desired conditions in any horizontal position of operation.

Referring to the embodiment of my invention illustrated in Figs, 9 to 11, inclusive, there is shown a cut-out device 42 similar to that designated 42 or 42 and illustrated in Figs. 2 to '7, inclusive, except that the boat thereof is shaped somewhat different from the boat 51, so that a part 59 of the fusible material is provided, which is so small in section that more than a few attempts to start the lamp by incandescing the filamentary elecrodes 23 and 24 will cause said section to melt due to its ohmic resistance, even though the whole of the material has not become sufficiently hot to melt as by conduction from the lead section 48 or radiation from the filament. Otherwise, the construction and operation of the present embodiment may correspond with that of the first.

Fig. 12 discloses a construction which may be identical with that of Figs. 2 to '7, inclusive, except that the cut-out device 42 is prevented from blowing during normal operation of the lamp, by being protected from the discharge by a shield SI of any suitable insulating material such as mica, rather than by a coating of aluminum, and the conductor portion 48 is made abnormally large in section to more efficiently conduct heat to the fusible material 54 for melting it, while the conductor 43 is restricted, as indicated at 60, to minimize conduction of heat to the flare 25.

Fig. 13 discloses a construction corresponding to that of Figs. 3 and 4 except that the cut-out device 42 is disposed with its axis angularly about half way between the positions of the devices 42 and 42, so as to be effective whether the lamp is positioned as in Fig. l or when rotated 90 about its axis.

From the foregoing disclosure it will be seen that I have devised a discharged lamp, which may be one of the well-known fluorescent lamps, having incorporated therewith a fuse which opens its starting circuit when it is defective, deactivated, or has reached the point where it should be replaced by a new one, as indicated by its failure to start after a reasonable number of attempts.

The advantages of my invention, as compared with previously known constructions, are that it is necessary to use only a glow relay with the lamp without the customary thermal switch, there is no starting current loss during operation of the lamp, or after operation of my cut-out device, the device is simple and efficient in removing every lamp from service when not in condition for efiicient operation, and the failure of the lamp is corrected within the lamp itself, rather than by some auxiliary device.

Although preferred embodiments of my invention have been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

I claim:

1. The method of manufacturing and mounting a cut-out device for a lamp comprising bending a sheet of readily fusible metal to approximately U shape, fitting it inside of an insulating boat so that it lines the sides thereof adjacent one end, passing a lead-in conductor through an aperture in the bottom of said boat, bending said conductor over the edge of said boat so that it holds an intermediate portion of said sheet against the end portion of said boat, passing another lead-in conductor through another aperture in the bottom of said boat adjacent the other end, mounting said device within the envelope of said lamp, and heating while said boat is in upwardly opening position, so that said metal melts and electrically unites said lead-in conductors.

2. The method of manufacturing and mounting a cut-out device for a lamp comprising fitting a piece of readily fusible metal into an insulating boat, passing a lead-in conductor through an aperture in the bottom and adjacent one end of said boat, bending said conductor so that it holds said metal in place, passing another lead-in conductor through another aperture in the bottom and adjacent the other end of said boat, mounting said device within the envelope of said lamp, and heating while said boat is in upwardly opening position, so that said metal melts and electrically unites said lead-in conductors.

3. In combination, an electric discharge lamp comprising anenvelope enclosing a pair of electron-emissive filamentary electrodes in an ionizable medium, and a circuit for applying filamentheating current and starting potential to said lamp, comprising leads connecting one terminal of each electrode through an inductor to a source of power, leads connecting the other terminals of said filamentary electrodes through a glow relay device comprising a bimetallic electrode normally separated from an associated electrode and adapted, upon the application of a suitable lamp potential, to develop a glow discharge causing heating and resultant contact between said relay electrodes, to heat the filamentary electrodes to electron-emissive temperature for the purpose of initiating a discharge therebetween, said bimetallic electrode after making contact with its associated electrode, breaking said contact upon cooling to provide a voltage surge for starting said lamp, and a low-fusing-point conductor inside of said envelope, adjacent, and in series with a lead to, one of said electrodes, whereby only when the lamp fails to start upon repeated operations of said glow relay device, the filamentary electrode heating current effects such a transfer of heat to said low-fusing-point conductor, that it melts and opens the. lamp starting circuit.

ALFRED H. LAIDIG. 

